US20140001909A1 - Rotating electrical machine - Google Patents
Rotating electrical machine Download PDFInfo
- Publication number
- US20140001909A1 US20140001909A1 US13/930,055 US201313930055A US2014001909A1 US 20140001909 A1 US20140001909 A1 US 20140001909A1 US 201313930055 A US201313930055 A US 201313930055A US 2014001909 A1 US2014001909 A1 US 2014001909A1
- Authority
- US
- United States
- Prior art keywords
- circumferential direction
- permanent magnet
- electrical machine
- rotating electrical
- tooth portions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
- H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2746—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets arranged with the same polarity, e.g. consequent pole type
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/278—Surface mounted magnets; Inset magnets
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
- H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
- H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information
Definitions
- the present disclosure relates to a rotating electrical machine.
- Permanent magnet materials such as rare-earth magnets have high energy density and therefore are essential materials to reduce the size of an electrical machine. However, it is hard to obtain an adequate amount of permanent magnet materials due to uneven distribution of resources in the world. For this reason, machines have been designed to reduce use of permanent magnet materials as much as possible.
- a consequent-pole rotor is employed to reduce use of permanent magnet materials.
- the consequent-pole rotor has projections, projecting radially outward from a boss portion, and permanent magnets located between adjacent projections.
- the present inventor finds out that if a rotating electrical machine is designed by employing magnetic circuit data disclosed in US 2011/0285243, a variation in rotation of a rotor may occur.
- cogging torque may be increased.
- the magnetic circuit data is specialized for output torque.
- the width of the permanent magnet is much greater than the width of the projection. This causes a disturbance in the space magnetic field distribution, and the disturbance results in the increase in the cogging torque.
- the present inventor finds out that the increase in the cogging torque is closely related to an interaction among the permanent magnet, the projection, and a tooth portion of a stator.
- a rotating electrical machine includes a supporting member, a stator core, a winding, a rotation shaft, a rotor core, and permanent magnets.
- the stator core includes a ring-shaped yoke fixed to the supporting member and tooth portions projecting from the yoke in a radial inward direction. Each tooth portion has a base joined to the yoke and an end opposite to the base. The winding is wound in a slot between the tooth portions.
- the rotation shaft extends through the stator core and rotatably supported by the supporting member.
- the rotor core includes a boss portion and projections. The boss portion is fixed to the rotation shaft.
- the projections project from the boss portion in a radial outward direction and spaced from each other in a circumferential direction.
- the permanent magnets are fixed to the boss portion. Each permanent magnet is located between and spaced from adjacent projections to form a gap in the circumferential direction. A width of the gap in the circumferential direction is equal to or smaller than a width of the end of the tooth portion in the circumferential direction.
- FIG. 1 is a diagram illustrating a cross-sectional view of an electrical motor according to a first embodiment of the present disclosure
- FIG. 2 is a diagram illustrating a cross-sectional view taken along line II-II in FIG. 1 ;
- FIG. 3 is a diagram illustrating an enlarged view of a region III in FIG. 2 ;
- FIG. 4 is a diagram illustrating a comparison in cogging torque between the motor according to the first embodiment and a motor according to a first comparison example shown in FIG. 12 ;
- FIG. 5 is a diagram illustrating a cross-sectional view of an electrical motor according to a second embodiment of the present disclosure
- FIG. 6 is a diagram illustrating an enlarged view of a region VI in FIG. 5 ;
- FIG. 7 is a diagram illustrating a comparison in efficiency between the motor according to the second embodiment and the motor according to the first comparison example
- FIG. 8 is a diagram illustrating a partial enlarged cross-sectional view of an electrical motor according to a third embodiment of the present disclosure.
- FIG. 9 is a diagram illustrating a comparison in output torque between the motor according to the third embodiment and the motor according to the first comparison example
- FIG. 10 is a diagram illustrating a cross-sectional view of an electrical motor according to a fourth embodiment of the present disclosure.
- FIG. 11 is a diagram illustrating an enlarged view of a region XI in FIG. 10 ;
- FIG. 12 is a diagram illustrating a change in magnetic flux over time in the motor according to the first comparison example
- FIG. 13 is a diagram illustrating a change in magnetic flux over time in a motor according to a second comparison example.
- FIG. 14 is a diagram illustrating a waveform of magnetic flux in a tooth portion of each of the motors of FIGS. 12 and 13 .
- FIG. 12 shows a change in magnetic flux over time t1 to t3 in a first comparison example in which a gap between a permanent magnet 101 and a projection 102 of a rotor in a circumferential direction is small.
- FIG. 13 shows a change in magnetic flux over time t1 to t3 in a second comparison example in which a gap between a permanent magnet 104 and a projection 105 of a rotor in a circumferential direction is large.
- a gap between a permanent magnet and a projection of a rotor in a circumferential direction be as large as possible.
- a gap between the permanent magnet 104 and a projection 105 of the rotor in the circumferential direction is too large, an end of a tooth portion 106 of a stator in a radial inward direction cannot adequately bypass between magnetic poles.
- main magnetic flux does not always flow in the tooth portions 103 .
- a magnetized condition varies largely depending on a rotor position so that cogging torque can become large.
- a waveform of magnetic flux in the tooth portion 106 of the second comparison example shown in FIG. 13 is distorted largely and contains a lot of harmonics. Therefore, magnetic flux rotating in a stator varies so that cogging torque can become large.
- a motor 1 (as a rotating electrical machine) according to a first embodiment of the present disclosure is described below with reference to FIGS. 1 and 2 .
- the motor 1 is a three-phase brushless motor.
- the motor 1 includes a housing 10 , a stator 20 , and a rotor 30 .
- the housing 10 includes a tube 11 , a first side portion 12 , and a second side portion 14 .
- a first end of the tube 11 is closed with the first side portion 12 .
- a second end of the tube 11 is closed with the second side portion 14 .
- a bearing 16 is fitted in a through hole 13 in the center of the first side portion 12 .
- a bearing 17 is fitted in a through hole 15 in the center of the second side portion 14 .
- the stator 20 includes a stator core 21 and a winding set 22 .
- the stator core 21 is located in the tube 11 of the housing 10 .
- the winding set 22 is wound on the stator core 21 .
- the stator core 21 has a yoke 24 and tooth portions 25 .
- the yoke 24 is pressed into the tube 11 so that the yoke 24 can be pressed against and fixed to an inner surface of the tube 11 .
- the tooth portions 25 project from the yoke 24 in a radial inward direction of the yoke 24 .
- the yoke 24 and the tooth portions 25 are formed as a single piece.
- the stator core 21 has twenty-four tooth portions 25 . That is, the number of the tooth portions 25 for every magnetic pole and every phase is one.
- the tooth portions 25 are arranged at a regular interval in a circumferential direction of the yoke 24 .
- the winding set 22 includes a U-phase winding, a V-phase winding, and a W-phase winding.
- a slot 28 is formed between adjacent tooth portions 25 .
- Each winding of the winding set 22 is wound in every third slot 25 .
- each winding of the winding set 22 is wound at intervals of three slots 25 .
- FIG. 2 shows a direction of an electric current flowing through the U-phase winding only.
- the rotor 30 is a consequent-pole rotor.
- the rotor 30 includes a rotation shaft 31 , a rotor core 32 , and permanent magnets 40 .
- the shaft 31 is rotatably supported by the bearings 16 and 17 .
- the rotor core 32 is made from soft magnetic material.
- the rotor core 32 includes a boss portion 33 and projections 34 .
- the boss portion 33 is fixed to the shaft 31 , for example, by press-fitting the shaft 31 into the boss portion 33 .
- the projections 34 project from the boss portion 33 in a radial outward direction of the boss portion 33 and are spaced from each other in a circumferential direction of the boss portion 33 .
- the projections 34 serve as soft magnetic poles.
- the rotor core 32 is made of steel plates that are laminated in a direction of an axis ⁇ of the shaft 31 .
- the permanent magnets 40 are fixed to the boss portion 33 . Each permanent magnet 40 is located between and spaced from adjacent projections 34 to form a gap 50 in the circumferential direction.
- the boss portion 33 of the rotor core 32 serves as a magnetic flux conductor for conducting a magnetic flux expelled from the permanent magnet 40 .
- the magnetic flux expelled from the permanent magnet 40 consists of a main flux and a leakage flux.
- the main flux flows from the permanent magnet 40 to the projection 34 through the tooth portions 25 and the yoke 24 .
- the leakage flux flows in a lateral direction from the permanent magnet 40 to the projection 34 through the tooth portions 25 and does not flow through the yoke 24 .
- each winding of the winding set 22 is connected to a power converter (not shown) including an inverter, a controller, and a battery and energized in turn so that a magnetic field rotating in the circumferential direction can be generated.
- the rotor 30 rotates according to the rotating magnetic field.
- stator 20 and the rotor 30 are described in detail with reference to FIGS. 2 and 3 .
- a width W 1 of the gap 50 between the permanent magnet 40 and the projection 34 in the circumferential direction is smaller than a width W 2 of an end of the tooth portion 25 in the circumferential direction. It is noted that the width W 1 is an outermost width of the gap 50 in the radial outward direction and that the width W 2 is an innermost width of the end of the tooth portion 25 in the radial inward direction.
- an end surface of the permanent magnet 40 in the circumferential direction is defined as a first end surface 41
- an end surface of the projection 34 in the circumferential direction is defined as a second end surface 35
- an imaginary plane formed as an extension of the first end surface 41 is defined as a first imaginary plane IP 1
- an imaginary plane formed as an extension of the second end surface 35 is defined as a second imaginary plane IP 2 .
- the tooth portion 25 in the circumferential direction and a center of the gap 50 in the circumferential direction are aligned with each other in the radial direction (i.e., are on the same straight line in the radial direction)
- the tooth portion 25 is positioned within a region defined by the first imaginary plane IP 1 and the second imaginary plane IP 2 .
- each permanent magnet 40 has two first end surfaces 41 opposite to each other in the circumferential direction.
- the two first end surfaces 41 of the permanent magnet 40 are parallel to each other.
- each projection 34 has two second end surfaces 35 opposite to each other in the circumferential direction.
- the two second end surfaces 35 of the projection 34 are parallel to each other.
- a distance between the first end surface 41 and the second end surface 35 which face each other to form the gap 50 , increases in the radial outward direction. Accordingly, a width of the region defined by the first imaginary plane IP 1 and the second imaginary plane IP 2 increases in the radial outward direction.
- a width of the permanent magnet 40 in the circumferential direction is equal to a width of the projection 34 in the circumferential direction.
- each of the other gaps 50 is positioned to face any one of the other tooth portions 25 in the radial direction.
- the number of the tooth portions 25 for every magnet pole and every phase is defined as “k”
- the number of the tooth portions 25 capable of facing each permanent magnet 40 in the radial direction is (3k ⁇ 1)
- the number of the tooth portions 25 capable of facing each projection 34 in the radial direction is (3k ⁇ 1). Since the number k is one, the number (3k ⁇ 1) is two.
- the width W 1 of the gap 50 between the permanent magnet 40 and the projection 34 in the circumferential direction is smaller than the width W 2 of the end of the tooth portion 25 in the circumferential direction. Further, when the center of the tooth portion 25 in the circumferential direction and the center of the gap 50 in the circumferential direction are aligned with each other in the radial direction, the tooth portion 25 is positioned within the region defined by the first imaginary plane IP 1 and the second imaginary plane IP 2 .
- the permanent magnets 40 and the projections 34 form a magnetic bypass having a suitable magnetic reluctance.
- cogging torque observed when no current is supplied to the winding set 22 is reduced.
- output torque observed when a rated current is supplied to the winding set 22 is increased.
- cogging torque in the first embodiment is about one-tenth of cogging torque in the first comparison example shown in FIG. 12 .
- the opposing first end surfaces 41 of the permanent magnet 40 are parallel to each other, and the opposing second end surfaces 35 of the projection 34 are parallel to each other.
- the distance between the first end surface 41 and the second end surface 35 , which face each other to form the gap 50 increases in the radial outward direction.
- the width W 2 of the end of the tooth portion 25 in the circumferential direction can be increased as much as possible. Therefore, the magnetic flux flowing from the permanent magnet 40 to the stator core 21 can be easily collected by the tooth portion 25 .
- the width of the permanent magnet 40 in the circumferential direction is equal to the width of the projection 34 in the circumferential direction. Accordingly, each gap 50 has the same width in the circumferential direction, and the gaps 50 are arranged at regular intervals in the circumferential direction. Thus, when any one of the gaps 50 is positioned to face any one of the tooth portions 25 in the radial direction, each of the other gaps 50 can be positioned to face any one of the other tooth portions 25 in the radial direction. Therefore, synchronizing timing in the circumferential direction becomes equal so that the cogging torque can be reduced without a reduction in the output torque.
- the number k which is the number of the tooth portions 25 for every magnet pole and every phase, is one, and the number of the tooth portions 25 capable of facing each permanent magnet 40 in the radial direction is (3k ⁇ 1), which is two.
- the output torque can be maximized while reducing the cogging torque as much as possible.
- a motor 60 according to a second embodiment of the present disclosure is described below with reference to FIGS. 5 and 6 .
- a difference of the second embodiment from the first embodiment is as follows.
- a stator core 62 of a stator 61 of the motor 60 includes the yoke 24 and twenty-four tooth portions 63 .
- Each tooth portion 63 has a leg 64 and a flange 65 .
- the leg 64 extends from the yoke 24 in the radial inward direction.
- the flange 65 extends from an end of the leg 64 in both directions along the circumferential direction.
- the width W 1 of the gap 50 between the permanent magnet 40 and the projection 34 in the circumferential direction is smaller than a width W 3 of the flange 65 in the circumferential direction. Further, when a center of the flange 65 in the circumferential direction and the center of the gap 50 in the circumferential direction are aligned with each other in the radial direction (i.e., are on the same straight line in the radial direction), the flange 65 is positioned within the region defined by the first imaginary plane IP 1 and the second imaginary plane IP 2 .
- each of the other gaps 50 is positioned to face any one of the other tooth portions 63 in the radial direction.
- the number of the tooth portions 63 for every magnet pole and every phase is defined as “k”
- the number of the tooth portions 63 capable of facing each permanent magnet 40 in the radial direction is (3k ⁇ 1)
- the number of the tooth portions 63 capable of facing each projection 34 in the radial direction is (3k ⁇ 1). Since the number k is one, the number (3k ⁇ 1) is two.
- the motor 60 of the second embodiment can have the same advantages as the motor 1 of the first embodiment. Further, since the slot 66 can be widened by narrowing the leg 64 of the tooth portion 63 up to the magnetic saturation limit, electrical loading can be increased. Thus, copper loss is reduced so that efficiency can be improved. For example, as shown in FIG. 7 , the motor 60 is 8 percent more efficient than the first comparison example shown in FIG. 12 . Accordingly, the size of the motor 60 can be reduced.
- a motor 70 according to a third embodiment of the present disclosure is described below with reference to FIG. 8 .
- a difference of the third embodiment from the preceding embodiments is as follows.
- the motor 70 includes the stator 61 and a rotor 74 .
- An end 71 of the tooth portion 63 of the stator core 62 in the radial inward direction is separated by a first distance D 1 in the radial direction from an end 73 of an outer surface 72 of the permanent magnet 40 in the circumferential direction.
- the end 71 of the tooth portion 63 of the stator core 62 in the radial inward direction is separated by a second distance D 2 in the radial direction from an end 78 of an outer surface 77 of a projection 76 of the rotor 74 in the circumferential direction.
- the first distance D 1 is smaller than the second distance D 2 .
- a distance between the end 71 of the tooth portion 63 and a center of the outer surface 72 of the permanent magnet 40 is equal to a distance between the end 71 of the tooth portion 63 and a center of the outer surface 77 of the projection 76 .
- a curvature radius R 1 of the outer surface 72 of the permanent magnet 40 is larger than a curvature radius R 2 of the outer surface 77 of the projection 76 .
- a width W 4 of a gap 79 between the permanent magnet 40 and the projection 76 in the circumferential direction is smaller than the width W 3 of the flange 65 in the circumferential direction.
- each of the other gaps 79 is positioned to face any one of the other tooth portions 63 in the radial direction.
- the number of the tooth portions 63 for every magnet pole and every phase is defined as “k”
- the number of the tooth portions 63 capable of facing each permanent magnet 40 in the radial direction is (3k ⁇ 1)
- the number of the tooth portions 63 capable of facing each projection 76 in the radial direction is (3k ⁇ 1). Since the number k is one, the number (3k ⁇ 1) is two.
- the motor 70 of the third embodiment can have the same advantages as the motor 1 of the first embodiment. Further, since the magnetic resistance can be increased by increasing the gap in the leakage flux path, the leakage flux can be effectively reduced. For example, as shown in FIG. 9 , output torque of the motor 70 is 3/2 (i.e., 1.5) times greater than that of the first comparison example shown in FIG. 12 . Accordingly, the size of the motor 60 can be reduced.
- the rotor core 75 can be made by stamping steel into a predetermined shaped plate and by laminating the steel plates.
- the curvature radius R 2 of the outer surface 77 of the projection 76 can be easily made smaller than the curvature radius R 1 of the outer surface 72 of the permanent magnet 40 .
- a motor 80 according to a fourth embodiment of the present disclosure is described below with reference to FIGS. 10 and 11 .
- a difference of the fourth embodiment from the preceding embodiments is as follows.
- the motor 80 includes a stator 81 and a rotor 86 .
- a stator core 82 of the stator 81 includes the yoke 24 and tooth portions 83 .
- Each tooth portion 83 has a leg 84 and a flange 85 .
- the leg 84 extends from the yoke 24 in the radial inward direction.
- the flange 85 extends from an end of the leg 84 in both directions along the circumferential direction.
- a width W 6 of a gap 90 between a permanent magnet 87 and a projection 89 of the rotor 86 in the circumferential direction is smaller than a width W 5 of the flange 85 in the circumferential direction.
- the flange 85 is positioned within a region defined by a first imaginary plane IP 3 and a second imaginary plane IP 4 .
- the first imaginary plane IP 3 is a plane formed as an extension of an end surface of the permanent 87 in the circumferential direction.
- the second imaginary plane IP 4 is a plane formed as an extension of an end surface of the projection 89 in the circumferential direction.
- the stator core 82 has forty-eight tooth portions 83 . Therefore, the number of the tooth portions 83 for every magnetic pole and every phase is two.
- the tooth portions 83 are arranged at regular intervals in the circumferential direction.
- the number of the tooth portions 83 for every magnet pole and every phase is defined as “k”
- the number of the tooth portions 83 capable of facing each permanent magnet 87 in the radial direction is (3k ⁇ 1)
- the number of the tooth portions 83 capable of facing each projection 89 of the rotor core 88 in the radial direction is (3k ⁇ 1). Since the number k is two, the number (3k ⁇ 1) is five.
- each of the other gaps 90 is positioned to face any one of the other tooth portions 83 in the radial direction.
- the motor 80 of the fourth embodiment can have the same advantages as the motor 1 of the first embodiment. Further, since the width of the flange 85 of the tooth portion 83 in the circumferential direction can be reduced, the width of the gap 90 in the circumferential direction can be reduced accordingly. As the width of the gap 90 in the circumferential direction becomes smaller, the widths of the permanent magnet 87 and the projection 89 in the circumferential direction become larger. Thus, magnetic loading can be increased so that output torque of the motor 80 can be increased.
- the number of poles of the rotor is not limited to eight.
- the number of phases is not limited to eight.
- the number of tooth portions for every magnet pole and every phase can vary depending on the intended use.
- the rotor is not limited to a surface permanent magnet type rotor.
- the rotor can be an embedded permanent magnet type rotor.
- the rotor can have a consequent-pole type structure partially in the axis direction.
- the width of the gap between the permanent magnet and the projection in the circumferential direction can be equal to the width of the end of the tooth portion in the circumferential direction.
- a full pitch, distributed winding is employed.
- a different winding design such as a short pitch, distributed winding can be employed.
- the rotor core is made by laminating steel plates.
- the rotor core can be made by a different method.
- the rotor core can be made by compression molding of magnetic powders.
- the rotating electrical machine to which the present disclosure is applied is not limited to a motor.
- the rotating electrical machine can be an alternator.
- cogging torque can be reduced without a reduction in output electrical power.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Iron Core Of Rotating Electric Machines (AREA)
- Permanent Field Magnets Of Synchronous Machinery (AREA)
- Permanent Magnet Type Synchronous Machine (AREA)
Abstract
Description
- This application is based on Japanese Patent Application No. 2012-146673 filed on Jun. 29, 2012, the disclosure of which is incorporated herein by reference.
- The present disclosure relates to a rotating electrical machine.
- Permanent magnet materials such as rare-earth magnets have high energy density and therefore are essential materials to reduce the size of an electrical machine. However, it is hard to obtain an adequate amount of permanent magnet materials due to uneven distribution of resources in the world. For this reason, machines have been designed to reduce use of permanent magnet materials as much as possible. For example, in a rotating electrical machine disclosed in JP-A-2011-250508 corresponding to US 2011/0285243, a consequent-pole rotor is employed to reduce use of permanent magnet materials. The consequent-pole rotor has projections, projecting radially outward from a boss portion, and permanent magnets located between adjacent projections.
- After deep analysis of the rotating electrical machine disclosed in US 2011/0285243, the present inventor finds out that if a rotating electrical machine is designed by employing magnetic circuit data disclosed in US 2011/0285243, a variation in rotation of a rotor may occur. In particular, when the rotating electrical machine is used in an electrical power steering system of a vehicle, cogging torque may be increased. In a technique disclosed in US 2011/0285243, the magnetic circuit data is specialized for output torque. Specifically, the width of the permanent magnet is much greater than the width of the projection. This causes a disturbance in the space magnetic field distribution, and the disturbance results in the increase in the cogging torque. In summary, the present inventor finds out that the increase in the cogging torque is closely related to an interaction among the permanent magnet, the projection, and a tooth portion of a stator.
- In view of the above, it is an object of the present disclosure to provide a rotating electrical machine for reducing cogging torque without a reduction in output torque.
- According to an aspect of the present disclosure, a rotating electrical machine includes a supporting member, a stator core, a winding, a rotation shaft, a rotor core, and permanent magnets. The stator core includes a ring-shaped yoke fixed to the supporting member and tooth portions projecting from the yoke in a radial inward direction. Each tooth portion has a base joined to the yoke and an end opposite to the base. The winding is wound in a slot between the tooth portions. The rotation shaft extends through the stator core and rotatably supported by the supporting member. The rotor core includes a boss portion and projections. The boss portion is fixed to the rotation shaft. The projections project from the boss portion in a radial outward direction and spaced from each other in a circumferential direction. The permanent magnets are fixed to the boss portion. Each permanent magnet is located between and spaced from adjacent projections to form a gap in the circumferential direction. A width of the gap in the circumferential direction is equal to or smaller than a width of the end of the tooth portion in the circumferential direction.
- The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
-
FIG. 1 is a diagram illustrating a cross-sectional view of an electrical motor according to a first embodiment of the present disclosure; -
FIG. 2 is a diagram illustrating a cross-sectional view taken along line II-II inFIG. 1 ; -
FIG. 3 is a diagram illustrating an enlarged view of a region III inFIG. 2 ; -
FIG. 4 is a diagram illustrating a comparison in cogging torque between the motor according to the first embodiment and a motor according to a first comparison example shown inFIG. 12 ; -
FIG. 5 is a diagram illustrating a cross-sectional view of an electrical motor according to a second embodiment of the present disclosure; -
FIG. 6 is a diagram illustrating an enlarged view of a region VI inFIG. 5 ; -
FIG. 7 is a diagram illustrating a comparison in efficiency between the motor according to the second embodiment and the motor according to the first comparison example; -
FIG. 8 is a diagram illustrating a partial enlarged cross-sectional view of an electrical motor according to a third embodiment of the present disclosure; -
FIG. 9 is a diagram illustrating a comparison in output torque between the motor according to the third embodiment and the motor according to the first comparison example; -
FIG. 10 is a diagram illustrating a cross-sectional view of an electrical motor according to a fourth embodiment of the present disclosure; -
FIG. 11 is a diagram illustrating an enlarged view of a region XI inFIG. 10 ; -
FIG. 12 is a diagram illustrating a change in magnetic flux over time in the motor according to the first comparison example; -
FIG. 13 is a diagram illustrating a change in magnetic flux over time in a motor according to a second comparison example; and -
FIG. 14 is a diagram illustrating a waveform of magnetic flux in a tooth portion of each of the motors ofFIGS. 12 and 13 . - Firstly, a cause of an increase in cogging torque found out by the present inventor is described below with reference to
FIGS. 12 , 13, and 14. -
FIG. 12 shows a change in magnetic flux over time t1 to t3 in a first comparison example in which a gap between apermanent magnet 101 and aprojection 102 of a rotor in a circumferential direction is small.FIG. 13 shows a change in magnetic flux over time t1 to t3 in a second comparison example in which a gap between apermanent magnet 104 and aprojection 105 of a rotor in a circumferential direction is large. - As shown in
FIG. 12 , when the gap between thepermanent magnet 101 and theprojection 102 of the rotor in the circumferential direction is small, an end of atooth portion 103 of a stator in a radial inward direction magnetically bypasses between magnetic poles easily. Thus, as indicated by broken lines inFIG. 12 , a certain amount of main magnetic flux always flows in thetooth portion 103 so that cogging torque observed when no current is supplied can become small. However, since lateral magnetic flux (i.e., leakage magnetic flux) is increased, a reduction in output torque observed when a rated current is supplied is large. - Therefore, it is preferable that a gap between a permanent magnet and a projection of a rotor in a circumferential direction be as large as possible. However, as shown in
FIG. 13 , when the gap between thepermanent magnet 104 and aprojection 105 of the rotor in the circumferential direction is too large, an end of atooth portion 106 of a stator in a radial inward direction cannot adequately bypass between magnetic poles. Thus, as indicated by broken lines inFIG. 13 , main magnetic flux does not always flow in thetooth portions 103. As a result, a magnetized condition varies largely depending on a rotor position so that cogging torque can become large. - As indicated by a solid line in
FIG. 14 , a waveform of magnetic flux in thetooth portion 106 of the second comparison example shown inFIG. 13 is distorted largely and contains a lot of harmonics. Therefore, magnetic flux rotating in a stator varies so that cogging torque can become large. - On the other hand, as indicated by a broken line in
FIG. 14 , a waveform of magnetic flux in thetooth portion 103 of the first comparison example shown inFIG. 12 is distorted a little. However, since the crest value of the waveform is reduced, effective magnetic flux is reduced accordingly. This phenomenon appears pronouncedly when a permanent magnet is wider than a projection as disclosed in JP-A-2011-250508. - Next, embodiments of the present disclosure are described based on the above findings.
- A motor 1 (as a rotating electrical machine) according to a first embodiment of the present disclosure is described below with reference to
FIGS. 1 and 2 . As shown inFIG. 1 , themotor 1 is a three-phase brushless motor. Themotor 1 includes ahousing 10, astator 20, and arotor 30. - The
housing 10 includes atube 11, afirst side portion 12, and asecond side portion 14. A first end of thetube 11 is closed with thefirst side portion 12. A second end of thetube 11 is closed with thesecond side portion 14. Abearing 16 is fitted in a throughhole 13 in the center of thefirst side portion 12. Abearing 17 is fitted in a throughhole 15 in the center of thesecond side portion 14. - The
stator 20 includes astator core 21 and a windingset 22. Thestator core 21 is located in thetube 11 of thehousing 10. The winding set 22 is wound on thestator core 21. - The
stator core 21 has ayoke 24 andtooth portions 25. Theyoke 24 is pressed into thetube 11 so that theyoke 24 can be pressed against and fixed to an inner surface of thetube 11. Thetooth portions 25 project from theyoke 24 in a radial inward direction of theyoke 24. Theyoke 24 and thetooth portions 25 are formed as a single piece. According to the first embodiment, thestator core 21 has twenty-fourtooth portions 25. That is, the number of thetooth portions 25 for every magnetic pole and every phase is one. Thetooth portions 25 are arranged at a regular interval in a circumferential direction of theyoke 24. - The winding set 22 includes a U-phase winding, a V-phase winding, and a W-phase winding. A
slot 28 is formed betweenadjacent tooth portions 25. Each winding of the windingset 22 is wound in everythird slot 25. In other words, each winding of the windingset 22 is wound at intervals of threeslots 25. It is noted thatFIG. 2 shows a direction of an electric current flowing through the U-phase winding only. - The
rotor 30 is a consequent-pole rotor. Therotor 30 includes arotation shaft 31, arotor core 32, andpermanent magnets 40. - The
shaft 31 is rotatably supported by thebearings - The
rotor core 32 is made from soft magnetic material. Therotor core 32 includes aboss portion 33 andprojections 34. Theboss portion 33 is fixed to theshaft 31, for example, by press-fitting theshaft 31 into theboss portion 33. Theprojections 34 project from theboss portion 33 in a radial outward direction of theboss portion 33 and are spaced from each other in a circumferential direction of theboss portion 33. Theprojections 34 serve as soft magnetic poles. According to the first embodiment, therotor core 32 is made of steel plates that are laminated in a direction of an axis φ of theshaft 31. - The
permanent magnets 40 are fixed to theboss portion 33. Eachpermanent magnet 40 is located between and spaced fromadjacent projections 34 to form agap 50 in the circumferential direction. - The
boss portion 33 of therotor core 32 serves as a magnetic flux conductor for conducting a magnetic flux expelled from thepermanent magnet 40. The magnetic flux expelled from thepermanent magnet 40 consists of a main flux and a leakage flux. The main flux flows from thepermanent magnet 40 to theprojection 34 through thetooth portions 25 and theyoke 24. The leakage flux flows in a lateral direction from thepermanent magnet 40 to theprojection 34 through thetooth portions 25 and does not flow through theyoke 24. - In the
motor 1, each winding of the windingset 22 is connected to a power converter (not shown) including an inverter, a controller, and a battery and energized in turn so that a magnetic field rotating in the circumferential direction can be generated. Therotor 30 rotates according to the rotating magnetic field. - Next, the
stator 20 and therotor 30 are described in detail with reference toFIGS. 2 and 3 . - A width W1 of the
gap 50 between thepermanent magnet 40 and theprojection 34 in the circumferential direction is smaller than a width W2 of an end of thetooth portion 25 in the circumferential direction. It is noted that the width W1 is an outermost width of thegap 50 in the radial outward direction and that the width W2 is an innermost width of the end of thetooth portion 25 in the radial inward direction. Here, an end surface of thepermanent magnet 40 in the circumferential direction is defined as afirst end surface 41, an end surface of theprojection 34 in the circumferential direction is defined as asecond end surface 35, an imaginary plane formed as an extension of thefirst end surface 41 is defined as a first imaginary plane IP1, and an imaginary plane formed as an extension of thesecond end surface 35 is defined as a second imaginary plane IP2. According to the first embodiment, when a center of thetooth portion 25 in the circumferential direction and a center of thegap 50 in the circumferential direction are aligned with each other in the radial direction (i.e., are on the same straight line in the radial direction), thetooth portion 25 is positioned within a region defined by the first imaginary plane IP1 and the second imaginary plane IP2. - Specifically, each
permanent magnet 40 has two first end surfaces 41 opposite to each other in the circumferential direction. The two first end surfaces 41 of thepermanent magnet 40 are parallel to each other. Likewise, eachprojection 34 has two second end surfaces 35 opposite to each other in the circumferential direction. The two second end surfaces 35 of theprojection 34 are parallel to each other. A distance between thefirst end surface 41 and thesecond end surface 35, which face each other to form thegap 50, increases in the radial outward direction. Accordingly, a width of the region defined by the first imaginary plane IP1 and the second imaginary plane IP2 increases in the radial outward direction. - A width of the
permanent magnet 40 in the circumferential direction is equal to a width of theprojection 34 in the circumferential direction. When any one of thegaps 50 is positioned to face any one of thetooth portions 25 in the radial direction, each of theother gaps 50 is positioned to face any one of theother tooth portions 25 in the radial direction. When the number of thetooth portions 25 for every magnet pole and every phase is defined as “k”, the number of thetooth portions 25 capable of facing eachpermanent magnet 40 in the radial direction is (3k−1), and also the number of thetooth portions 25 capable of facing eachprojection 34 in the radial direction is (3k−1). Since the number k is one, the number (3k−1) is two. - As described above, according to the first embodiment, the width W1 of the
gap 50 between thepermanent magnet 40 and theprojection 34 in the circumferential direction is smaller than the width W2 of the end of thetooth portion 25 in the circumferential direction. Further, when the center of thetooth portion 25 in the circumferential direction and the center of thegap 50 in the circumferential direction are aligned with each other in the radial direction, thetooth portion 25 is positioned within the region defined by the first imaginary plane IP1 and the second imaginary plane IP2. - In such an approach, the
permanent magnets 40 and theprojections 34 form a magnetic bypass having a suitable magnetic reluctance. Thus, since the main flux always flows so that a magnetic field variation can be reduced, cogging torque observed when no current is supplied to the windingset 22 is reduced. Further, since the leakage flux is reduced, output torque observed when a rated current is supplied to the windingset 22 is increased. As shown inFIG. 4 , cogging torque in the first embodiment is about one-tenth of cogging torque in the first comparison example shown inFIG. 12 . - Further, according to the first embodiment, the opposing first end surfaces 41 of the
permanent magnet 40 are parallel to each other, and the opposing second end surfaces 35 of theprojection 34 are parallel to each other. - Accordingly, the distance between the
first end surface 41 and thesecond end surface 35, which face each other to form thegap 50, increases in the radial outward direction. Thus, the width W2 of the end of thetooth portion 25 in the circumferential direction can be increased as much as possible. Therefore, the magnetic flux flowing from thepermanent magnet 40 to thestator core 21 can be easily collected by thetooth portion 25. - Further, according to the first embodiment, the width of the
permanent magnet 40 in the circumferential direction is equal to the width of theprojection 34 in the circumferential direction. Accordingly, eachgap 50 has the same width in the circumferential direction, and thegaps 50 are arranged at regular intervals in the circumferential direction. Thus, when any one of thegaps 50 is positioned to face any one of thetooth portions 25 in the radial direction, each of theother gaps 50 can be positioned to face any one of theother tooth portions 25 in the radial direction. Therefore, synchronizing timing in the circumferential direction becomes equal so that the cogging torque can be reduced without a reduction in the output torque. - Further, according to the first embodiment, the number k, which is the number of the
tooth portions 25 for every magnet pole and every phase, is one, and the number of thetooth portions 25 capable of facing eachpermanent magnet 40 in the radial direction is (3k−1), which is two. Thus, the output torque can be maximized while reducing the cogging torque as much as possible. - A
motor 60 according to a second embodiment of the present disclosure is described below with reference toFIGS. 5 and 6 . A difference of the second embodiment from the first embodiment is as follows. - A
stator core 62 of astator 61 of themotor 60 includes theyoke 24 and twenty-fourtooth portions 63. Eachtooth portion 63 has aleg 64 and aflange 65. Theleg 64 extends from theyoke 24 in the radial inward direction. Theflange 65 extends from an end of theleg 64 in both directions along the circumferential direction. - The width W1 of the
gap 50 between thepermanent magnet 40 and theprojection 34 in the circumferential direction is smaller than a width W3 of theflange 65 in the circumferential direction. Further, when a center of theflange 65 in the circumferential direction and the center of thegap 50 in the circumferential direction are aligned with each other in the radial direction (i.e., are on the same straight line in the radial direction), theflange 65 is positioned within the region defined by the first imaginary plane IP1 and the second imaginary plane IP2. - Further, when any one of the
gaps 50 is positioned to face any one of thetooth portions 63 in the radial direction, each of theother gaps 50 is positioned to face any one of theother tooth portions 63 in the radial direction. Further, when the number of thetooth portions 63 for every magnet pole and every phase is defined as “k”, the number of thetooth portions 63 capable of facing eachpermanent magnet 40 in the radial direction is (3k−1), and also the number of thetooth portions 63 capable of facing eachprojection 34 in the radial direction is (3k−1). Since the number k is one, the number (3k−1) is two. - The
motor 60 of the second embodiment can have the same advantages as themotor 1 of the first embodiment. Further, since theslot 66 can be widened by narrowing theleg 64 of thetooth portion 63 up to the magnetic saturation limit, electrical loading can be increased. Thus, copper loss is reduced so that efficiency can be improved. For example, as shown inFIG. 7 , themotor 60 is 8 percent more efficient than the first comparison example shown inFIG. 12 . Accordingly, the size of themotor 60 can be reduced. - A
motor 70 according to a third embodiment of the present disclosure is described below with reference toFIG. 8 . A difference of the third embodiment from the preceding embodiments is as follows. - The
motor 70 includes thestator 61 and arotor 74. Anend 71 of thetooth portion 63 of thestator core 62 in the radial inward direction is separated by a first distance D1 in the radial direction from anend 73 of anouter surface 72 of thepermanent magnet 40 in the circumferential direction. Theend 71 of thetooth portion 63 of thestator core 62 in the radial inward direction is separated by a second distance D2 in the radial direction from anend 78 of anouter surface 77 of aprojection 76 of therotor 74 in the circumferential direction. The first distance D1 is smaller than the second distance D2. Specifically, a distance between theend 71 of thetooth portion 63 and a center of theouter surface 72 of thepermanent magnet 40 is equal to a distance between theend 71 of thetooth portion 63 and a center of theouter surface 77 of theprojection 76. Further, a curvature radius R1 of theouter surface 72 of thepermanent magnet 40 is larger than a curvature radius R2 of theouter surface 77 of theprojection 76. - A width W4 of a
gap 79 between thepermanent magnet 40 and theprojection 76 in the circumferential direction is smaller than the width W3 of theflange 65 in the circumferential direction. When any one of thegaps 79 is positioned to face any one of thetooth portions 63 in the radial direction, each of theother gaps 79 is positioned to face any one of theother tooth portions 63 in the radial direction. Further, when the number of thetooth portions 63 for every magnet pole and every phase is defined as “k”, the number of thetooth portions 63 capable of facing eachpermanent magnet 40 in the radial direction is (3k−1), and also the number of thetooth portions 63 capable of facing eachprojection 76 in the radial direction is (3k−1). Since the number k is one, the number (3k−1) is two. - The
motor 70 of the third embodiment can have the same advantages as themotor 1 of the first embodiment. Further, since the magnetic resistance can be increased by increasing the gap in the leakage flux path, the leakage flux can be effectively reduced. For example, as shown inFIG. 9 , output torque of themotor 70 is 3/2 (i.e., 1.5) times greater than that of the first comparison example shown inFIG. 12 . Accordingly, the size of themotor 60 can be reduced. - For example, like the first embodiment, the
rotor core 75 can be made by stamping steel into a predetermined shaped plate and by laminating the steel plates. In such an approach, the curvature radius R2 of theouter surface 77 of theprojection 76 can be easily made smaller than the curvature radius R1 of theouter surface 72 of thepermanent magnet 40. - A
motor 80 according to a fourth embodiment of the present disclosure is described below with reference toFIGS. 10 and 11 . A difference of the fourth embodiment from the preceding embodiments is as follows. - The
motor 80 includes astator 81 and arotor 86. Astator core 82 of thestator 81 includes theyoke 24 andtooth portions 83. Eachtooth portion 83 has aleg 84 and aflange 85. Theleg 84 extends from theyoke 24 in the radial inward direction. Theflange 85 extends from an end of theleg 84 in both directions along the circumferential direction. - A width W6 of a
gap 90 between apermanent magnet 87 and aprojection 89 of therotor 86 in the circumferential direction is smaller than a width W5 of theflange 85 in the circumferential direction. Further, when a center of theflange 85 in the circumferential direction and a center of thegap 90 in the circumferential direction are aligned with each other in the radial direction (i.e., are on the same straight line in the radial direction), theflange 85 is positioned within a region defined by a first imaginary plane IP3 and a second imaginary plane IP4. The first imaginary plane IP3 is a plane formed as an extension of an end surface of the permanent 87 in the circumferential direction. The second imaginary plane IP4 is a plane formed as an extension of an end surface of theprojection 89 in the circumferential direction. - The
stator core 82 has forty-eighttooth portions 83. Therefore, the number of thetooth portions 83 for every magnetic pole and every phase is two. Thetooth portions 83 are arranged at regular intervals in the circumferential direction. When the number of thetooth portions 83 for every magnet pole and every phase is defined as “k”, the number of thetooth portions 83 capable of facing eachpermanent magnet 87 in the radial direction is (3k−1), and also the number of thetooth portions 83 capable of facing eachprojection 89 of therotor core 88 in the radial direction is (3k−1). Since the number k is two, the number (3k−1) is five. When any one of thegaps 90 is positioned to face any one of thetooth portions 83 in the radial direction, each of theother gaps 90 is positioned to face any one of theother tooth portions 83 in the radial direction. - The
motor 80 of the fourth embodiment can have the same advantages as themotor 1 of the first embodiment. Further, since the width of theflange 85 of thetooth portion 83 in the circumferential direction can be reduced, the width of thegap 90 in the circumferential direction can be reduced accordingly. As the width of thegap 90 in the circumferential direction becomes smaller, the widths of thepermanent magnet 87 and theprojection 89 in the circumferential direction become larger. Thus, magnetic loading can be increased so that output torque of themotor 80 can be increased. - While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
- The number of poles of the rotor is not limited to eight. The number of phases is not limited to eight. The number of tooth portions for every magnet pole and every phase can vary depending on the intended use.
- The rotor is not limited to a surface permanent magnet type rotor. The rotor can be an embedded permanent magnet type rotor.
- The rotor can have a consequent-pole type structure partially in the axis direction.
- The width of the gap between the permanent magnet and the projection in the circumferential direction can be equal to the width of the end of the tooth portion in the circumferential direction.
- In the embodiments, a full pitch, distributed winding is employed. Alternatively, a different winding design such as a short pitch, distributed winding can be employed.
- In the embodiments, the rotor core is made by laminating steel plates. Alternatively, the rotor core can be made by a different method. For example, the rotor core can be made by compression molding of magnetic powders.
- The rotating electrical machine to which the present disclosure is applied is not limited to a motor. For example, the rotating electrical machine can be an alternator. When the present disclosure is applied to an alternator, cogging torque can be reduced without a reduction in output electrical power.
Claims (10)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012146673A JP5605721B2 (en) | 2012-06-29 | 2012-06-29 | Rotating electric machine |
JP2012-146673 | 2012-06-29 |
Publications (2)
Publication Number | Publication Date |
---|---|
US20140001909A1 true US20140001909A1 (en) | 2014-01-02 |
US9106115B2 US9106115B2 (en) | 2015-08-11 |
Family
ID=49777386
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/930,055 Active 2034-04-22 US9106115B2 (en) | 2012-06-29 | 2013-06-28 | Rotating electrical machine |
Country Status (3)
Country | Link |
---|---|
US (1) | US9106115B2 (en) |
JP (1) | JP5605721B2 (en) |
CN (1) | CN103532328B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
PL422728A1 (en) * | 2017-09-02 | 2019-03-11 | Natalia Julia Sobolewska | BLCLDC T Brushless Commutatorless Direct Current Motor |
PL422805A1 (en) * | 2017-09-11 | 2019-03-25 | Joanna Paulina Sobolewska | BLCLDC SH Brushless Commutatorless Direct Current Motor |
PL423608A1 (en) * | 2017-11-25 | 2019-06-03 | Joanna Paulina Sobolewska | BLCLDC SH EXT Brushless Commutatorless Direct Current Motor |
US11456632B2 (en) * | 2016-07-15 | 2022-09-27 | Mitsubishi Electric Corporation | Consequent-pole type rotor, electric motor, air conditioner, and method for manufacturing consequent-pole type rotor |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP7080703B2 (en) * | 2018-04-12 | 2022-06-06 | 株式会社ミツバ | Motors and brushless wiper motors |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5631512A (en) * | 1994-04-13 | 1997-05-20 | Toyota Jidosha Kabushiki Kaisha | Synchronous motor having magnetic poles of permanent magnet and magnetic poles of a soft magnetic material |
US20100148612A1 (en) * | 2008-12-17 | 2010-06-17 | Asmo Co., Ltd. | Brushless motor |
US20110285243A1 (en) * | 2010-05-24 | 2011-11-24 | Denso Corporation | Rotary electric machine with improved magnetic resistance |
US20110309707A1 (en) * | 2010-06-17 | 2011-12-22 | Asmo Co., Ltd. | Motor |
US8502430B2 (en) * | 2010-11-11 | 2013-08-06 | Asmo Co., Ltd. | Rotor and motor |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2938385B1 (en) * | 2008-11-10 | 2013-02-15 | Peugeot Citroen Automobiles Sa | ROTATING ELECTRICAL MACHINE WITH DOUBLE EXCITATION OF HOMOPOLAR TYPE |
JP5513059B2 (en) * | 2009-10-07 | 2014-06-04 | アスモ株式会社 | Rotor and motor |
CN102035330B (en) | 2009-10-07 | 2014-09-24 | 阿斯莫有限公司 | Motor |
JP5611680B2 (en) * | 2010-06-17 | 2014-10-22 | アスモ株式会社 | motor |
JP5483582B2 (en) * | 2010-07-21 | 2014-05-07 | アスモ株式会社 | motor |
US8643239B2 (en) | 2010-07-21 | 2014-02-04 | Asmo Co., Ltd. | Motor |
-
2012
- 2012-06-29 JP JP2012146673A patent/JP5605721B2/en not_active Expired - Fee Related
-
2013
- 2013-06-28 CN CN201310264431.4A patent/CN103532328B/en not_active Expired - Fee Related
- 2013-06-28 US US13/930,055 patent/US9106115B2/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5631512A (en) * | 1994-04-13 | 1997-05-20 | Toyota Jidosha Kabushiki Kaisha | Synchronous motor having magnetic poles of permanent magnet and magnetic poles of a soft magnetic material |
US20100148612A1 (en) * | 2008-12-17 | 2010-06-17 | Asmo Co., Ltd. | Brushless motor |
US20110285243A1 (en) * | 2010-05-24 | 2011-11-24 | Denso Corporation | Rotary electric machine with improved magnetic resistance |
US20110309707A1 (en) * | 2010-06-17 | 2011-12-22 | Asmo Co., Ltd. | Motor |
US8502430B2 (en) * | 2010-11-11 | 2013-08-06 | Asmo Co., Ltd. | Rotor and motor |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11456632B2 (en) * | 2016-07-15 | 2022-09-27 | Mitsubishi Electric Corporation | Consequent-pole type rotor, electric motor, air conditioner, and method for manufacturing consequent-pole type rotor |
PL422728A1 (en) * | 2017-09-02 | 2019-03-11 | Natalia Julia Sobolewska | BLCLDC T Brushless Commutatorless Direct Current Motor |
PL422805A1 (en) * | 2017-09-11 | 2019-03-25 | Joanna Paulina Sobolewska | BLCLDC SH Brushless Commutatorless Direct Current Motor |
PL423608A1 (en) * | 2017-11-25 | 2019-06-03 | Joanna Paulina Sobolewska | BLCLDC SH EXT Brushless Commutatorless Direct Current Motor |
Also Published As
Publication number | Publication date |
---|---|
CN103532328B (en) | 2016-11-16 |
JP2014011880A (en) | 2014-01-20 |
CN103532328A (en) | 2014-01-22 |
JP5605721B2 (en) | 2014-10-15 |
US9106115B2 (en) | 2015-08-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9006949B2 (en) | Synchronous motor | |
Li et al. | Elimination of even-order harmonics and unipolar leakage flux in consequent-pole PM machines by employing NS-iron–SN-iron rotor | |
JP5774081B2 (en) | Rotating electric machine | |
US7514833B2 (en) | Axial gap permanent-magnet machine with reluctance poles and PM element covers | |
JP5682600B2 (en) | Rotating electrical machine rotor | |
US7569962B2 (en) | Multi-phase brushless motor with reduced number of stator poles | |
JP5796569B2 (en) | Rotor and rotating electric machine using the same | |
Zhu et al. | Distortion of back-EMF and torque of PM brushless machines due to eccentricity | |
US9692265B2 (en) | Variable magnetic flux-type rotary electric machine | |
US20060175923A1 (en) | Rotary electric machine comprising a stator and two rotors | |
CN108432091B (en) | Electric motor | |
RU2641722C1 (en) | Rotating electrical machine and stator of rotating electrical machine | |
JP5347588B2 (en) | Embedded magnet motor | |
US9106115B2 (en) | Rotating electrical machine | |
JP6048191B2 (en) | Multi-gap rotating electric machine | |
JP2014531191A (en) | Rotating electrical machine rotor and rotating electrical machine with rotor | |
JP6406355B2 (en) | Double stator type rotating machine | |
US20210135554A1 (en) | Novel double-stator combined electric machine suitable for achieving sensorless control of absolute position of rotor | |
US20140145539A1 (en) | Permanent magnet synchronous electric machine | |
JP2010200480A (en) | Embedded magnetic motor | |
US20190181705A1 (en) | Rotor and method for designing rotor | |
US8987971B2 (en) | Rotor core for an electric machine | |
JPH11136892A (en) | Permanent magnet motor | |
Hua et al. | Investigation on symmetrical characteristics of consequent-pole flux reversal permanent magnet machines with concentrated windings | |
JP5582149B2 (en) | Rotor, rotating electric machine and generator using the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: DENSO CORPORATION, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TANIGUCHI, MAKOTO;REEL/FRAME:030707/0211 Effective date: 20130605 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 8 |